5Center for AIDS and Sexually Transmitted Diseases, University of Washington, Seattle 98104, USA

Correspondence to: D Halperin

Accepted 19 January 2004

Behaviour change programmes to prevent HIV have mainly promoted condom use or abstinence, while partner reduction remains the neglected component of ABC

The key to preventing the spread of HIV, especially in epidemics driven mainly by heterosexual transmission, is through changing sexual behaviour. Interest has been growing in an “ABC” approach in which A stands for abstinence or delay of sexual activity, B for be faithful, and C for condom use (box).1 Although “be faithful” literally implies monogamy, it also includes reductions in casual sex and multiple sexual partnerships (and related issues of partner selection) that would reduce higher risk sex. While most of the often polarised discussion surrounding AIDS prevention has focused on promoting abstinence or use of condoms,w1 w2 partner reduction has been the neglected middle child of the ABC approach.

Epidemiological importance of partner reduction

It seems obvious, but there would be no global AIDS pandemic were it not for multiple sexual partnerships. The rate of change of sexual partners—especially concurrent partners—is a crucial determinant in the spread of sexually transmitted infections,w3 including HIV.2 Moreover, HIV viral load and therefore infectiousness is dramatically higher during the early (acute) stage of HIV infection,3 so transmission would be particularly heightened by partner change among newly infected people. Transmission of HIV is also facilitated by the presence of other sexually transmitted infections, especially ulcerative ones.w4 Hence, increased risk of other sexually transmitted infections from multiple partnerships further magnifies the spread of HIV.